Imaging apparatus and electronic apparatus

ABSTRACT

The present disclosure relates to an imaging apparatus and an electronic apparatus that are capable of receiving light a plurality of times temporally per pulse emission. After instructing a light emitting unit to perform pulse emission, a control unit instructs an image sensor to start exposure at a time T 11 =(2×D 11 )/c, finish exposure at a time T 21 =(2×D 21 )/c, start exposure at a time T 12 =(2×D 12 )/c, finish exposure at a time T 22 =(2×D 22 )/c, start exposure at a time T 13 =(2×D 13 )/c, and finish exposure at a time T 21 =(2×D 23 )/c. The present disclosure is applicable to, for example, a gated imaging apparatus that is an apparatus that emits pulsed light and performs imaging for only a specific time period.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase of International PatentApplication No. PCT/JP2017/014455 filed on Apr. 7, 2017, which claimspriority benefit of Japanese Patent Application No. 2016-086216 filed inthe Japan Patent Office on Apr. 22, 2016. Each of the above-referencedapplications is hereby incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to an imaging apparatus and an electronicapparatus, and particularly to an imaging apparatus and an electronicapparatus that are capable of receiving light a plurality of timestemporally per pulse emission.

BACKGROUND ART

There is an imaging technology known by the name of Active GatedImaging, Active Imaging, Range-gated Active Imaging, or the like. It iscalled gated imaging in Japanese, and will be referred to as the gatedimaging hereinafter.

The gated imaging is a technology capable of sharply imaging only asubject at a specific distance by emitting pulsed light and picking upan image by an image sensor for only a specific time period.

In this technology, in the case where there are a plurality of subjects,it has been necessary to pick up an image a plurality of times as shownin patent Literature 1.

CITATION LIST Patent Literature

Patent Literature 1: WO 2013-179280

DISCLOSURE OF INVENTION Technical Problem

That is, in the case where there are a plurality of subjects, forexample, it has been difficult to perform appropriate gated imaging.

The present disclosure has been made in view of the above circumstancesto be capable of receiving light a plurality of times temporally perpulse emission.

Solution to Problem

An imaging apparatus according to an aspect of the present technologyincludes: a light emitting unit that performs pulse emission; a lightreception unit that receives light; an exposure control unit that causesthe light reception unit to perform a plurality of times of exposure perpulse emission from the light emitting unit; and a setting unit thatsets, depending on a predetermined imaging distance range, a start timeand an end time of the plurality of times of exposure by using timing ofthe pulse emission as a reference to perform imaging processing on asubject within the predetermined imaging distance range.

The predetermined imaging distance range may include one to n (n beingan integer not less than 2) imaging distance ranges, and when the i-th(i=1 to n) distance range of the predetermined imaging distance range isrepresented by Min(i) to Max(i) (Min(i)<Max(i)), the number of times ofthe exposure may be n, and the setting unit may set a start time and anend time of the j-th (j=1 to n) exposure of the n times of exposure to(2×Min(i))/c and (2×Max(i))/c (c representing a speed of light),respectively.

An amount of light received by the light reception unit may be stored inany of 1 to m (m representing an integer not less than 2) memories, andwhen the predetermined imaging distance range is represented by Min toMax (Min<Max), the number of times of the exposure may be m, the settingunit may set a start time and an end time of the j-th (j=1 to n)exposure of the m times of exposure to (2×Min)/c+2×(Max−Min)×(j−1)/c/mand 2×Min/c+2×(Max−Min)×j/c/m (c representing a speed of light),respectively, and the control unit may perform such control that anamount of light received in the j-th (j=1 to n) exposure of the m timesof exposure is stored in the j-th memory of the m memories.

The imaging apparatus may further include a subject identification unitthat identifies a memory storing no data of a projected image of thesubject out of the m memories, in which in a case where the memorystoring no data of the projected image of the subject identified by thesubject identification unit is the p-th memory and p=m or psubstantially equals to m, a smaller value may be reset for at least oneof a value of the Min and a value of the Max, and a parameter for nextimaging may be determined, or in a case where the memory storing no dataof the projected image of the subject identified by the subjectidentification unit is the p-th memory and p=1 or p substantially equalsto 1, a larger value may be reset for at least one of a value of the Minand a value of the Max, and a parameter for next imaging may bedetermined.

In each of s+1 (s representing an integer not less than 1) times ofimaging processing on the subject, an amount of light received by thelight reception unit may be stored in any of a first memory and a secondmemory, the predetermined imaging distance range may include 1 to (2 tothe s-th power) imaging distance ranges, and when the k-th (k=1 to 2 tothe s-th power) distance range of the predetermined imaging distancerange is represented by Min(k) to Max(k) (Min(k)<Max(k)), the number oftimes of the exposure may be 2×(2 to the s-th power), the setting unitmay set a start time and an end time of the 2×k−1-th (k=1 to 2 to thes-th power) exposure of the (2 to the s-th power) times of exposure to2×Min(k)/c, 2×Max(k)/c+2×(Max(k)−Min(k)/c/2, and 2×Max(k)/c (crepresenting a speed of light), respectively, and set a start time andan end time of the 2×k-th (k=1 to 2 to the s-th power) exposure of the(2 to the s-th power)times of exposure to2×Min(k)/c+2×(Max(k)−Min(k))/c/ and 2×Max(k)/c (c representing a speedof light), and in the q-th (q representing 1 to s+1) imaging processing,the control unit may perform such control that an amount of lightreceived by the light reception unit in the 2×k−1-th (k=1 to 2 to thes-th power) exposure of the (2 to the s-th power) times of exposure isstored in the r(k,q)-th (r(k,q) representing 1 or 2) memory of the firstmemory and the second memory, and an amount of light received by thelight reception unit in the 2×k-th (k=1 to 2 to the s-th power) exposureof the (2 to the s-th power) times of exposure is stored in a memoryother than the r(k,q)-th (r(k,q) representing 1 or 2) memory of thefirst memory and the second memory, and determine r(k,q) so that asequence {r(k,1), r(k,2), . . . r(k,s+1)} is different from a sequence{r(k′,1), r(k′,2), . . . r(k′,s+1): where k′≠k} and a sequence{3−r(k′,1), r(k′,2), . . . r(k′,s+1: where k′≠k) for k being anarbitrary value.

The imaging apparatus may further include a subject identification unitthat identifies a memory storing no data of a projected image of thesubject out of the first memory and the second memory, in which in eachof s+1 (s representing an integer not less than 1) times of imagingprocessing on the subject, the setting unit may reset, corresponding tothe number of the memory storing no data of the projected image of thesubject identified by the subject identification unit, a smaller valuefor at least one of a value of the Min and a value of the Max, anddetermine a parameter for next imaging.

The imaging apparatus may further include a subject identification unitthat identifies the j-th (j=1 to n) memory storing data of a projectedimage of the subject out of the m memories, in which when the number ofthe memory storing the data of the projected image of the subjectidentified by the subject identification unit is q, the setting unit maynewly set the Min to 2×Min/c+2×(Max−Min)×(q−1)/c/m and the Max to2×Min/c+2×(Max−Min)×q/c/m (c representing a speed of light), anddetermine a parameter for next imaging.

An electronic apparatus according to an aspect of the present technologyincludes: a light emitting unit that performs pulse emission; a lightreception unit that receives light; an exposure control unit that causesthe light reception unit to perform a plurality of times of exposure perpulse emission from the light emitting unit; and a setting unit thatsets, depending on a predetermined imaging distance range, a start timeand an end time of the plurality of times of exposure by using timing ofthe pulse emission as a reference to perform imaging processing on asubject within the predetermined imaging distance range.

In an aspect of the present technology, a light reception unit thatreceives light is caused to perform a plurality of times of exposure perpulse emission. Then, a start time and an end time of the plurality oftimes of exposure are set depending on a predetermined imaging distancerange by using timing of the pulse emission as a reference to performimaging processing on a subject within the predetermined imagingdistance range.

Advantageous Effects of Invention

According to the present technology, it is possible to image a subject.In particular, according to the present technology, it is possible tosharply image a plurality of subjects.

It should be noted that the effects described herein are merelyexamples, and the effects of the present technology are not limited tothe effects described herein, and additional effects may be provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing a schematic configuration example of asolid-state imaging apparatus to which the present technology isapplied.

FIG. 2 is a diagram showing an overview of the gated imaging.

FIG. 3 is a diagram describing the gated imaging.

FIG. 4 is a diagram showing an example of the gated imaging in the casewhere there are a plurality of subjects.

FIG. 5 is a block diagram showing a configuration example of a gatedimaging apparatus to which the present technology is applied.

FIG. 6 is a diagram showing a configuration example of a pixel.

FIG. 7 is a diagram showing a configuration example of a firstembodiment of a gated imaging system to which the present technology isapplied.

FIG. 8 is a diagram showing another structural example of a mountingsubstrate to which the present technology is applied.

FIG. 9 is a diagram showing an example in the case where the gatedimaging apparatus according to the present technology is mounted on anautomobile.

FIG. 10 is a diagram showing a configuration example of a secondembodiment of the gated imaging system to which the present technologyis applied.

FIG. 11 is a diagram describing the case where a subject moves forward.

FIG. 12 is a flowchart describing gated imaging processing by the gatedimaging system shown in FIG. 10.

FIG. 13 is a flowchart describing the gated imaging processing by thegated imaging system shown in FIG. 10

FIG. 14 is a diagram describing a specific example of use of the secondembodiment of the present technology.

FIG. 15 is a diagram showing a configuration example of a thirdembodiment of the gated imaging system to which the present technologyis applied.

FIGS. 16A, 16B, and 16C are diagrams showing a control method.

FIG. 17 is a diagram showing a combination of patterns.

FIG. 18 is a diagram describing an important point of the thirdembodiment of the present technology in detail.

FIG. 19 is a diagram describing a method of identifying a moved subject.

FIG. 20 is a diagram describing a method of setting the time of the nextgated imaging.

FIG. 21 is a diagram describing a method of setting the time of the nextgated imaging.

FIG. 22 is a flowchart describing the gated imaging processing by thegated imaging system shown in FIG. 15.

FIG. 23 is a flowchart describing the gated imaging processing by thegated imaging system in the case of a fourth embodiment of the presenttechnology.

FIG. 24 is a flowchart describing processing of sub-routine A in StepS303 shown in FIG. 23.

FIG. 25 is a flowchart describing the processing of the sub-routine A inStep S303 shown in FIG. 23.

FIG. 26 is a flowchart describing the processing of the sub-routine A inStep S303 shown in FIG. 23.

FIG. 27 is a diagram showing a usage example of an image sensor to whichthe present technology is applied.

FIG. 28 is a block diagram showing a configuration example of anelectronic apparatus to which the present technology is applied.

MODE(S) FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments for carrying out the present disclosure(hereinafter, referred to as embodiments) will be described. Note thatdescriptions will be made in the following order.

0. Overview

1. First Embodiment

2. Second Embodiment

3. Third Embodiment

4. Fourth Embodiment

5. Fifth Embodiment (usage example of image sensor)

6. Sixth Embodiment (example of electronic apparatus)

0. Overview

<Schematic Configuration Example of Solid-State Imaging Apparatus>

FIG. 1 shows a schematic configuration example of an example of a CMOS(Complementary Metal Oxide Semiconductor) solid-state imaging apparatusapplied to each embodiment of the present technology.

As shown in FIG. 1, a solid-state imaging apparatus (device chip) 1includes a pixel area (so-called imaging area) 3 in which pixels 2 eachincluding a plurality of photoelectric conversion devices are regularlytwo-dimensionally arranged on a semiconductor substrate 11 (e.g.,silicon substrate), and a peripheral circuit area.

The pixels 2 each include the photoelectric conversion devices (e.g.,PDs (Photo Diodes)) and a plurality of pixel transistors (so-called MOStransistors). The plurality of pixel transistors may include, forexample, three transistors of a transfer transistor, a reset transistor,and an amplification transistor, or four transistors including aselection transistor in addition thereto.

Further, the pixels 2 may each have a pixel sharing structure. The pixelsharing structure includes a plurality of photodiodes, a plurality oftransfer transistors, one floating diffusion to be shared, and anotherpixel transistor to be shared. The photodiodes are each a photoelectricconversion device.

The peripheral circuit area includes a vertical drive circuit 4, columnsignal processing circuits 5, a horizontal drive circuit 6, an outputcircuit 7, and a control circuit 8.

The control circuit 8 receives an input clock and data for commanding anoperation mode or the like, and outputs data such as internalinformation of the solid-state imaging apparatus 1. Specifically, thecontrol circuit 8 generates, on the basis of a vertical synchronoussignal, a horizontal synchronous signal, and a master clock, a clocksignal and a control signal as a reference of operations of the verticaldrive circuit 4, the column signal processing circuits 5, and thehorizontal drive circuit 6. Then, the control circuit 8 inputs thesesignals to the vertical drive circuit 4, the column signal processingcircuits 5, and the horizontal drive circuit 6.

The vertical drive circuit 4 includes, for example, a shift register,selects a pixel driving line, supplies a pulse for driving the pixels 2to the selected pixel driving line, and drives the pixels 2 row by row.Specifically, the vertical drive circuit 4 sequentially selects andscans each pixel 2 of the pixel area 3 row by row in the verticaldirection, and supplies a pixel signal based on a signal chargegenerated depending on the mount of received light in the photoelectricconversion device of each pixel 2 to the column signal processingcircuit 5 via a vertical signal line 9.

The column signal processing circuits 5 are arranged for each column ofthe pixels 2, for example, and performs signal processing such as noiseremoval on a signal output from the pixels 2 in one row for each pixelcolumn. Specifically, the column signal processing circuit 5 performssignal processing such as CDS (Correlated Double Sampling) for removingthe pattern noise unique to the pixels 2, signal amplification, and A/D(Analog/Digital) conversion. At the output stage of the column signalprocessing circuit 5, a horizontal selection switch (not shown)connected with a horizontal signal line 10 is provided.

The horizontal drive circuit 6 includes, for example, a shift register,selects each of the column signal processing circuits 5 in order bysequentially outputting a horizontal scanning pulse, and causes eachcolumn signal processing circuit 5 to output a pixel signal to thehorizontal signal line 10.

The output circuit 7 performs signal processing on the signalsequentially supplied from each of the column signal processing circuits5 via the horizontal signal line 10, and outputs the signal. The outputcircuit 7 performs, for example, only buffering, or performs black leveladjusting, column variation correction, various types of digital signalprocessing, and the like in some cases.

Input/output terminals 12 are provided to transmit/receive signalsto/from the outside.

<Overview of Gated Imaging>

The present technology is a technology related to the gated imaging. Thegated imaging is a technology capable of sharply imaging only a subjectat a specific distance by emitting pulsed light and picking up an imageby an image sensor for only a specific time. For example, the gatedimaging is known by the name of Active Gated Imaging, Active Imaging,Range-gated Active Imaging or the like.

The gated imaging will be described with reference to FIG. 2. In theexample shown in FIG. 2, a gated imaging apparatus 21 includes a controlunit 31, a light emitting unit 32, and an imaging unit 33. The controlunit 31 controls the light emission timing of the light emitting unit 32and the exposure time period of the imaging unit 33. The light emittingunit 32 emits light having a rectangular wave form. The imaging unit 33exposes a subject 23. In such a gated imaging apparatus 21, it ispossible to image the subject 23 beyond a fog 22.

That is, in the case where the light emitting unit 32 emits light havinga rectangular wave form, reflected light from the fog 22 reaches theimaging unit 33 first, and then, reflected light from the subject 23reaches the imaging unit 33.

Note that in the case of a normal imaging unit, the exposure time periodis from when light having a rectangular wave form is emitted to whenreflected light from the subject 23 reaches the imaging unit, and animage in which the subject 23 is hard to see (hazy image) is obtainedbecause total light of reflected light from the fog 22 and reflectedlight from the subject 23 is exposed.

Meanwhile, in the case of the imaging unit 33 that performs the gatedimaging, since the imaging unit 33 accurately performs exposure for aspecific time period, it is possible to image only the reflected lightfrom the subject 23, for example. Therefore, in the gated imaging, it ispossible to clearly image a subject in an image.

Next, the gated imaging will be specifically described with reference toFIG. 3. In the example shown in FIG. 3, a gated imaging system 50 isshown.

As the gated imaging system 50, a gated imaging apparatus 51, a fog 52,and a subject 53 are shown in order from the left in the figure.

In the example shown in FIG. 3, the gated imaging apparatus 51 includesa light emitting unit 61 that emits pulsed light, and an image sensor 62(the solid-state imaging apparatus 1 shown in FIG. 1). For example,assumption is made that the subject 53 is to be imaged by using thegated imaging apparatus 51. There is the fog 52 in front of the subject53 (i.e., between the gated imaging apparatus 51 and the subject 53).

In this case, as shown in FIG. 3, it is possible to receive onlyreflected light from the subject 53 without receiving reflected lightfrom the fog 52, by setting distances D1 and D2 (i.e., an exposure starttime T1=(2×D1)/c and an exposure start time T2=(2×D2)/c). As a result,it is possible to pick up a sharp projected image of the subject 53.Note that the c represents the speed of light, and the same applieshereinafter.

Further, “the distance to the fog 52”<D1<“the distance to the subject52”<D2. Since the time when pulsed light is returned from the fog 52after the pulsed light is emitted and reflected on the fog 52 is earlierthan the time T1=(2×D1)/c, the light is not received by the image sensor62.

Next, the gated imaging in the case where there are three subjects to beimaged in the gated imaging system 50 will be described with referenceto FIG. 4.

In order to image subjects 53-1 to 53-3, there is a need to determinethe distances D1 and D2 so that D1<“distance to the subject 53-1”<D2,D1<“distance to the subject 53-2”<D2, and D1<“distance to the subject53-3”<D2. That is, the exposure start time T1=(2×D1)/c and the exposurestart time T2=(2×D2)/c) are set as shown in FIG. 4. In this case, theimage sensor 62 receives also reflected light from a fog 52-1 and a fog52-2 shown in FIG. 4, and thus, it has been difficult to acquire a sharpimage of the subjects 53-1 to 53-3.

For example, in Patent Literature 1, in the case where there are aplurality of subjects, imaging is performed a plurality of times, and ithas been impossible to achieve this by only one imaging. That is, on theassumption that D11<“distance to the subject 53-1”<D21<“distance to thefog 52-1”<D12<“distance to the subject 53-2”<D22<“distance to the fog52-2”<D13<“distance to the subject 53-3”<D23, first, imaging needs to beperformed with D1=D11 and D2=D21, then, imaging needs to be performedwith D1=D12 and D2=D22, and finally, imaging needs to be performed withD1=D13 and D2=D23 (imaging needs to be performed a total of threetimes).

Further, in the case where a subject moves in the depth direction andmoves outside the range of D1 to D2, it cannot receive reflected lightfrom the subject, and loses sight of the subject in some cases. It goeswithout saying that D1 and D2 are reset appropriately depending on themovement of the subject in some cases, but, it has been difficult toperform the resetting because whether the subject has moved to the frontof D1 or to the back of D2 is unknown.

In this regard, in the present technology, light reception is performeda plurality of times temporally per pulse emission. Accordingly, it ispossible to sharply image a plurality of subjects, know the direction ofmovement of a subject in the depth direction, and continue to image amoving subject by following the moving subject.

FIG. 5 is a block diagram showing a configuration example of the gatedimaging apparatus to which the present technology is applied.

In the example shown in FIG. 5, a gated imaging apparatus 70 includes acontrol unit 71 and an output terminal 72 in addition to the lightemitting unit 61 and the image sensor 62 shown in FIG. 3. The controlunit 71 issues a control signal that controls the light emitting unit 61and the image sensor 62. The light emitting unit 61 emits pulsed lightin response to the control signal from the control unit 71. In responseto the control signal from the control unit 71, the image sensor 62performs processing of starting exposure and finishing exposure, andoutputs, from the output terminal 72, charges in each pixel accumulatedin the exposure. Note that although a lens is provided so as to focus infront of the image sensor 62 actually, illustration thereof is omittedto prevent the figure from being complicated. Similarly, also in thefollowing figures, illustration of the lens is omitted.

The image sensor 62 includes, for example, the solid-state imagingapparatus 1 including the plurality of pixels 2 shown in FIG. 1. Thenumber of pixels is usually several hundred to several thousand bothvertically and horizontally.

FIG. 6 shows a configuration of one pixel 2. Light exposed (received) ina PD (photodiode: light-receiving device) 81 is converted into charges,and the charges are accumulated in a memory (FD: charge accumulationunit) 82-1 or 82-2, which is switched by a switch 83. In the period oftime when no exposure is performed, and the charges are discharged(discarded) to a drain switched by the switch 83. This switch 83 iscontrolled by the control signal from the control unit 71.

Further, the charges accumulated in the memories 82-1 and 82-2 can beoutput by the output terminal 72 shown in FIG. 5. At the time ofoutputting the charges accumulated in the memories 82-1 and 82-2 to theoutput terminal 72, the charges disappear.

Note that an example where there are two memories has been described inthe example shown in FIG. 6, also the case where there are three or morememories is possible. However, in the case where there are three or morememories, the layout becomes complicated.

Further, in a first embodiment described below, the memory 82-2 is notused. That is, in the first embodiment, before starting the exposure orafter finishing the exposure, light (charges) received by the PD 81 isdiscarded to the drain. Then, the light received by the PD 81 isaccumulated in the memory 82-1 from when starting the exposure and towhen finishing the exposure. Note that in this configuration, in thecase of resuming the exposure after finishing the exposure, charges arefurther accumulated in the memory 82-1 by the present exposure inaddition to the charges accumulated so far. These controls are performedby the control signal from the control unit 71.

Note that in second to fourth embodiments described below, also thememory 82-2 is used.

1. First Embodiment

<Configuration of Gated Imaging System>

FIG. 7 is a diagram showing a configuration example of a firstembodiment of the gated imaging system to which the present technologyis applied.

In a gated imaging system 90 shown in FIG. 7, the subjects 53-1 to 53-3are imaged by using the gated imaging apparatus 70. There is no fog infront of the subject 53-1 (i.e., between the gated imaging apparatus 70and the subject 53-1). There is the fog 52-1 in front of the subject53-2 (i.e., between the subject 53-1 and the subject 53-2), and there isthe fog 52-2 in front of the subject 53-3 (i.e., between the subject53-2 and the subject 53-3).

Then, in the gated imaging system 90, exposure is performed a pluralityof times (three times in the example shown in FIG. 7) per pulseemission. Note that the control unit 71 includes, for example, anexposure control unit 91 that controls a plurality of times of exposure,and a setting unit 92 that sets the start time and the end time of theplurality of times of exposure. The setting unit 92 sets the start timeand the end time of the plurality of times of exposure depending on apredetermined imaging distance range in order to perform processing ofimaging a subject in the predetermined imaging distance range, forexample, by using the timing of the pulse emission as a reference.

In the gated imaging apparatus 70, after instructing the light emittingunit 61 to perform pulse emission, for example, the setting unit 92 setsthe following start time and end time of the plurality of times ofexposure. Then, the exposure control unit 91 controls the plurality oftimes of exposure of the image sensor 62.

Specifically, the start time and the end time of the plurality of timesof exposure are as follows.

Exposure is started at the time T11=(2×D11)/c and finished at the timeT21=(2×D21)/c.

Exposure is started at the time T12=(2×D12)/c and finished at the timeT22=(2×D22)/c.

Exposure is started at the time T13=(2×D13)/c and finished at the timeT21=(2×D23)/c. Note that the c represents the speed of light. Further,D11<“distance to the subject 53-1”<D21<“distance to the fog52-1”<D12<“distance to the subject 53-2”<D22<“distance to the fog52-2”<D13<“distance to the subject 53-3”.

Then, after the time T23, charges accumulated in the memory 82-1 of thepixel 2 of the image sensor 62 are read, and a resulting image I of thegated imaging is obtained from a value of the read pixel.

As shown in FIG. 7, reflected light from the subjects 53-1 to 53-3 isreceived, and reflected light from the fogs 52-1 and 52-2 is notreceived. Accordingly, it is possible to acquire sharp projected imagesof the subjects 53-1 to 53-3.

<Operation of Gated Imaging System>

Next, the gated imaging processing by the gated imaging system 90 shownin FIG. 7 will be described with reference to the flowchart of FIG. 8.

In Step S11, the setting unit 92 specifies the number n of distanceranges to be imaged. Note that in the example shown in FIG. 7, n=3.

In Step S12, the setting unit 92 specifies n distance ranges to beimaged. Assumption is made that these distance ranges are Min(i) toMax(i) (i=1 to n). In the example shown in FIG. 7, Min(1)=D11,Max(1)=D21, Min(2)=D12, Max(2)=D22, Min(3)=D13, and Max(3)=D23.

In Step S13, the exposure control unit 91 switches the switch 83 to thedrain and starts to continue to transmit light exposed (chargesgenerated) in the PD 81 to the drain. That is, the charges are caused tobe discharged to the drain.

In Step S14, the exposure control unit 91 causes the output terminal 72to read charges in the memory 82-1 as dummy data in order to reset thecharges in the memory 82-1.

In Step S15, the exposure control unit 91 emits pulsed light from thelight emitting unit 61, and sets a parameter i to 1. In Step S16, theexposure control unit 91 stands by for only 2*Min(i)/c from the timewhen emitting the pulsed light, and starts exposure in Step S17. Thatis, the charges generated in the PD 81 start to be transmitted to thememory 82-1.

In Step S18, the exposure control unit 91 stands by for only 2*Max(i)/cfrom the time when emitting the pulsed light, and finishes the exposurein Step S19. That is, the charges generated in the PD 81 start to betransmitted to the drain.

In Step S20, the exposure control unit 91 determines whether or not i=n(it is repeated n times). In the case where it is determined in Step S20that i does not equal to n, the processing proceeds to Step S21. In StepS21, the exposure control unit 91 sets i=i+1, the processing returns toStep S16, and the subsequent processing is repeated.

In the case where it is determined in Step S20 that i=n, the processingproceeds to Step S22. In Step S22, the exposure control unit 91determines whether or not it is repeated a predetermined number oftimes. In the case where it is determined in Step S22 that it is notrepeated the predetermined number of times, the processing returns toStep S15 and the subsequent processing is repeated.

In the case where the exposure control unit 91 determines in Step S22that it is repeated the predetermined number of times, the processingproceeds to Step S23. In Step S23, the exposure control unit 91 readsthe charges in the memory 82-1 from the output terminal 72 to acquirethe resulting image I.

Note that since the amount of light by accumulation in one pulseemission is small, the same processing is performed only thepredetermined number of times (one light emission and the plurality oftimes of exposure in Steps S15 to S20), and the charges are accumulatedin the memory 82-1. With such accumulation, it is possible to achieve asufficient amount of light (charges). The predetermined number of timesis, for example, several hundred to several ten thousand.

Further, the longer the distance to the subject is, the weaker theamount of light that is emitted from the light emitting unit 61,reflected on the subject, and returned from the subject. Therefore, inthe example shown in FIG. 7, an image in which the subject 53-1 appearswith appropriate brightness but the subject 53-2 and the subject 53-3are dark is obtained in some cases.

In such a case, the gated imaging processing described with reference toFIG. 8 may be performed again (second gated imaging processing). In thissecond gated imaging processing, n=2, Min(1)=D12, Max(1)=D22,Min(2)=D13, and Max(2)=D23. Accordingly, it is possible to acquireprojected images of only the subjects 53-2 and 53-3. However, also inthis second gated imaging, since the subjects 53-2 and 53-3 are faraway, dark projected images are obtained. In this regard, by addingimages obtained by the first gated imaging and the second gated imaging,the brightness of the projected images of only the subjects 53-2 and53-3 is doubled, and the projected images become sharp.

By performing the gated imaging processing shown in FIG. 8 with thechanged parameter n and Min(i) to Max(i) (i=1 to n) and adding imagesobtained by the processing as described above, it is possible to acquirean image with appropriate brightness for a close subject and a distantsubject.

Note that the gated imaging apparatus 70 according to the presenttechnology can be mounted on an automobile and used for monitoring thefront. In this case, it is possible to constantly monitor the front bynot performing the gated imaging only one time but continuing to performthe gated imaging. The automobile moves by a distance Vc×Tc during thetime between the previous gated imaging and the next gated imaging. Inthis regard, for the next gated imaging, values of Min(i) to Max(i) (i=1to n) may be reduced by Vc×Tc than those used in the previous gatedimaging. By setting as described above, it is possible to continue toappropriately capture the subject even in the case where the gatedimaging apparatus 70 is moving.

<Another Configuration of Gated Imaging System>

Further, an example of the case where the gated imaging apparatus 70according to the present technology is mounted on an automobile will bespecifically described with reference to FIG. 9. Note that as aconfiguration example of the gated imaging apparatus 70, theconfiguration described with reference to FIG. 5 is used.

In the example shown in FIG. 9, a gated imaging system 100 at thepresent time is shown in the upper stage of the figure, and the gatedimaging system 100 after a time period Tc is shown in the lower stage ofthe figure.

Assumption is made that in the gated imaging system 100 at the presenttime, an automobile 101 on which the gated imaging apparatus 70 ismounted is moving in the right direction at a speed Vc. By appropriatelyperforming the gated imaging at the present time, pulsed light 111emitted from the light emitting unit 61 of the gated imaging apparatus70 is reflected on the subjects 53-1 to 53-3, and received by the imagesensor 63 as reflected light 112. Meanwhile, reflected light from thefogs 52-1 and 52-2 is not received by the image sensor 63. Accordingly,it is possible to acquire sharp projected images of the subjects 53-1 to53-3. This image is displayed in real time on a monitor (whoseillustration is omitted) in the automobile 101, and can support drivingof the automobile 101.

Next, the gated imaging is performed again after the time period Tc. Inthe gated imaging after the time period Tc, an automobile 101Tc hasmoved by only a distance Vc×Tc. That is, the distance between the gatedimaging apparatus 70 and the subjects 53-1 and 53-3 is reduced by onlyVc×Tc. In this regard, by reducing the values of Min(i) to Max(i) (i=1to n) by Vc×Tc as described above, pulsed light 111Tc emitted from thelight emitting unit 61 of the gated imaging apparatus 70 is reflected onthe subjects 53-1 to 53-3, and received by the image sensor 63 asreflected light 112Tc also in the gated imaging after the time periodTc. Reflected light from the fogs 52-1 and 52-2 is not received by theimage sensor 63. Accordingly, it is possible to acquire sharp projectedimages of the subjects 53-1 to 53-3. This image is displayed in realtime on a monitor (whose illustration is omitted) in the automobile101Tc, and can support driving of the automobile.

2. Second Embodiment

<Configuration of Gated Imaging System>

FIG. 10 is a diagram showing a configuration example of a secondembodiment of the gated imaging system to which the present technologyis applied.

In a gated imaging system 150 shown in FIG. 10, light (charges) exposed(received) by the PD 81 is accumulated in the memory 82-1 or 82-2 ordiscarded to the drain, at appropriate timing. Note that the gatedimaging system 150 shown in FIG. 10 is different from the gated imagingsystem 50 shown in FIG. 7 in that the control unit 71 further includes asubject determination unit 161 in addition to the exposure control unit91 and the setting unit 92. The subject determination unit 161determines (identifies) at what distance the subject is imaged bydetermining (identifying) in which memory the data of the projectedimage of the subject is (or is not).

In the example shown in FIG. 10, on the assumption that a distance tothe subject 53 is a distance D0, the time period to when pulsed light isreflected on the subject 53 and returned from the subject 53 isT0=2×D0/c. Assumption is made that the width of the pulsed light is awidth w, the pulsed light is emitted for the time period from time −W/2to time W/2, and T1=T0−W and T2=T0+W.

During the time T1 to the time T0, light (charges) exposed (received) bythe PD 81 is accumulated in the memory 82-1. During the time T0 to thetime T2, light (charges) exposed (received) by the PD 81 is accumulatedin the memory 82-2. During the other times, it is discharged to thedrain. In the gated imaging system 150 shown in FIG. 10, such control isperformed.

The first half of the emitted pulse (light emitted during the timeperiod from the time −W/2 to the time 0) is reflected on the subject 53,exposed (received) by the PD 81, and accumulated in the memory 82-1.

The latter half of the emitted pulse (light emitted during the timeperiod from the time 0 to the time W/2) is reflected on the subject 53,exposed (received) by the PD 81, and accumulated in the memory 82-2.

Then, after the time T2, charges accumulated in the memory 82-1 of eachpixel 2 of the image sensor 62 are read, and a resulting image I1 of thegated imaging is obtained from the value of the read pixel. Further,charges accumulated in the memory 82-2 of each pixel 2 of the imagesensor 62 are read, and a resulting image I2 of the gated imaging isobtained from the value of the read pixel.

In the resulting images I1 and I2, a projected image of the subject 53is picked up. Note that an image obtained by adding the resulting imageI1 and the resulting image I2 may be created to obtain a sharp image ofthe subject 53 in order to make it easy to see.

Now, next, as shown in FIG. 11, assumption is made that the subject 53moves forward.

In the example shown in FIG. 11, since the time period to when the lightis reflected on the subject 53 and returned from the subject 53 becomesearlier, a projected image of the subject 53 is picked up in theresulting image I1 but not in the resulting image I2.

That is, conversely, in the case where the subject 53 is imaged in theresulting image I1 but not in the resulting image I2, it is found thatthe subject 53 has moved forward. In this regard, in the case ofperforming the gated imaging again, the setting unit 92 only needs toset T0 to be larger than the previous value of T0 to perform the gatedimaging.

In the gated imaging system 150, in this way, it is possible to continueto perform the gated imaging while following the subject.

That is, according to the second embodiment of the present technology,even in the case where the subject moves in the depth direction, it ispossible to achieve the gated imaging capable of continuing to pick up asharp image by appropriately following the subject.

<Operation of Gated Imaging System>

Next, the gated imaging processing by the gated imaging system 150 shownin FIG. 10 and FIG. 11 will be described with reference to theflowcharts of FIG. 12 and FIG. 13.

In Step S111 in FIG. 12, the setting unit 92 specifies the distance D0at which imaging is to be performed. In Step S112, the exposure controlunit 91 switches the switch 83 to the drain, and starts to transmitcharges generated in the PD 81 to the drain. That is, the charges arecaused to be discharged to the drain.

In Step S113, the exposure control unit 91 causes the output terminal 72to read charges in the memory 82-1 as dummy data in order to reset thecharges in the memory 82-1, and causes the output terminal 72 to readcharges in the memory 82-2 as dummy data in order to reset the chargesin the memory 82-2.

The setting unit 92 sets T0=2*D0/c in Step S114, and sets T1=T0−W,T2=T0+W (note that W represents the width of pulsed light) in Step S115.

In Step S116 in FIG. 13, the exposure control unit 91 emits pulsed lightfrom the light emitting unit 61, stands by for only T1 from the timewhen emitting the pulsed light in Step S117, and starts exposure usingthe memory 82-1. That is, the charges generated by the PD 81 start to betransmitted to the memory 82-1.

In Step S119, the exposure control unit 91 stands by for only T0 fromthe time when emitting the pulsed light, and starts exposure using thememory 82-2 in Step S120. That is, the charges generated by the PD 81start to be transmitted to the memory 82-2.

The exposure control unit 91 stands by for only T2 from when emittingthe pulsed light in Step S121, and finishes the exposure in Step S122.That is, the charges generated by the PD 81 start to be transmitted tothe drain.

In Step S123, the exposure control unit 91 determines whether or not itis repeated a predetermined number of times. In the case where it isdetermined in Step S123 that it is not repeated the predetermined numberof times, the processing returns to Step S116, and the subsequentprocessing is repeated.

In the case where the exposure control unit 91 determines in Step S123that it is repeated the predetermined number of times, the processingproceeds to Step S124. In Step S124, the exposure control unit 91 readsthe charges in the memory 82-1 from the output terminal 72 to obtain theresulting image I1. Further, the exposure control unit 91 reads thecharges in the memory 82-2 from the output terminal 72 to obtain theresulting image I2.

In Step S125, the exposure control unit 91 outputs, as the resultingimage I of the present gated imaging, an image obtained by adding theresulting image I1 and the resulting image I2 from the output terminal72.

After that, in Step S126 in FIG. 12, the subject determination unit 161determines whether or not the contrast of the subject of the resultingimage I1 and the contrast of the subject of the resulting image I2 arethe same. In the case where it is determined in Step S126 that thecontrast of the subject of the resulting image I1 and the contrast ofthe subject of the resulting image I2 are the same, the processingproceeds to Step S127. In Step S127, the setting unit 92 sets δ=0.

In the case where it is determined in Step S126 that the contrast of thesubject of the resulting image I1 and the contrast of the subject of theresulting image I2 differ, the processing proceeds to Step S128. In StepS128, the setting unit 92 determines whether or not the resulting imageI1 has higher contrast.

In the case where it is determined in Step S128 that the resulting imageI1 has higher contrast, the processing proceeds to Step S129. In StepS129, the setting unit 92 sets δ=predetermined small negative value.

In the case where it is determined in Step S128 that the resulting imageI1 has lower contrast, the processing proceeds to Step S130. In StepS130, the setting unit 92 sets δ=predetermined small positive value.

After Step S127, Step S129, and Step S130, the processing proceeds toStep S131. In Step S131, the setting unit 92 sets T0=T0+δ, theprocessing returns to Step S115, and the subsequent processing isrepeated.

Note that in the gated imaging processing shown in FIG. 12 and FIG. 13,whether or not it is imaged in the resulting image I1 and whether or notin the resulting image I2, i.e., in which memory of the memories 82-1and 82-2 the data of a projected image is not is determined by usingprojected images of the two images.

Further, in the above description, the exposure time is represented bythe width W of pulsed light. It is not particularly limited to w, but itis favorably w. This is because by setting the exposure time to w, allthe pulsed light that is emitted from the light emitting unit 61 andreflected on the subject 53 is exposed, and it is not necessary toexpose reflected light from an object (e.g., fog that is not shown) thatis at another distance.

<Another Configuration of Gated Imaging System>

Further, a specific example of use of the second embodiment of thepresent technology will be described with reference to FIG. 14.

In a gated imaging system 200 shown in FIG. 14, a usage example formonitoring a prison is described. The inside of the prison and theoutside of the prison are separated by a wall 212. The gated imagingapparatus 70 is installed at a position away from the wall 212 to theoutside by the distance D0, and perform imaging in the direction of thewall 212.

Favorably, the gated imaging apparatus 70 may be installed on a pillar211 or the like so that the entire wall 212 can be seen from the gatedimaging apparatus 70. In the gated imaging system 200 configured asdescribed above, the gated imaging processing described above withreference to FIG. 12 and FIG. 13 is executed. In the case where there issomeone (subject 53 shown in FIG. 14) who climbs over the wall 212 fromthe inside and escapes to the outside and even in the case where thereis the fog 52, it is possible to acquire a sharp projected image of thesubject 53.

Further, in the gated imaging system 200, even in the case where thesubject 53 has moved, it is possible to continue to perform the gatedimaging processing by appropriately following the distance to thesubject 53. This is because the contrast of a projected part of thesubject 53 becomes higher from the moment when the subject 53 hasclimbed over the wall 212 and the gated imaging is continued to beperformed by following the distance for the higher contrast. In thisway, in the gated imaging system 200, it is possible to monitor thedesertion.

3. Third Embodiment

<Configuration of Gated Imaging System>

FIG. 15 is a diagram showing a configuration example of a thirdembodiment of the gated imaging system to which the present technologyis applied.

A gated imaging system 250 shown in FIG. 15 is different from the gatedimaging system 150 shown in FIG. 10 in that the control unit 71 includesa subject determination unit 261 instead of the subject determinationunit 161. The subject determination unit 261 determines (identifies)whether a subject in what distance has moved forward or backward bydetermining (identifying) in which memory the data of a projected imageof the subject is (or is not).

In the example shown in FIG. 15, the gated imaging is performed threetimes, and light (charges) exposed (received) by the PD 81 isaccumulated in the memory 82-1 or 82-2 or discarded to the drain atappropriate timing.

That is, the gated imaging is performed by a control method of controlC1 shown in the figure, the gated imaging is performed by a controlmethod of control C2 shown in the figure, and the gated imaging isperformed by a control method of control C3 shown in the figure. In thisway, the gated imaging is performed three times in total. From an imagegroup acquired by performing the gated imaging three times in total,whether a subject in what distance has moved forward or backward isdetermined by the subject determination unit 261, and parameters (T01 toT04 to be described later) for the next three times of gated imaging areupdated by the setting unit 92.

Note that although assumption is made that the gated imaging isperformed temporally three times in the following description, forexample, in the case where the resolution in the spatial direction maybe sacrificed, the gated imaging may be performed by a control method ofthe control C1 in the multiples-of-three line of the image sensor 62,the gated imaging may be performed by a control method of the control C2in the multiples-of-three-with-a-remainder-of-one line of the imagesensor 62, and the gated imaging may be performed by a control method ofthe control C3 in the multiples-of-three-with-a-remainder-of-two line ofthe image sensor 62. In this way, although the resolution is reduced to⅓, it is possible to acquire all images of the gated imaging of thecontrol C1 to the control C3 by one gated imaging.

In the example shown in FIG. 15, an example of the gated imaging forsharply imaging four subjects (subjects 53-1 to 53-4) is shown. Notethat even in the case where the subject has moved, it is possible tosharply perform imaging even in the next gated imaging by following thesubject.

On the assumption that the distance to the subject 53-I (i=1 to 4) is D0i, the time when the pulsed light is reflected on the subject 53-i andreturned from the subject 53-i is T0 i=2×D0 i/c. The width of the pulsedlight is represented by W. That is, assumption is made that the pulsedlight is emitted for the time period from the time −W/2 to the time W/2.Further, T1 i=T0 i−W and T2 i=T0 i+W.

First, in the first gated imaging, as shown in FIG. 16A, imaging isperformed by the method of the control 1. That is, light (charges)exposed by the PD (light-receiving device) 81 is accumulated in thememory 82-1 during the times T11 and T01. Light (charges) exposed by thePD (light-receiving device) 81 is accumulated in the memory 82-2 duringthe times T01 and T21.

Light (charges) exposed by the PD (light-receiving device) 81 isaccumulated in the memory 82-1 during the times T12 and T02. Light(charges) exposed by the PD (light-receiving device) 81 is accumulatedin the memory 82-2 during the times T02 and T22.

Light (charges) exposed by the PD (light-receiving device) 81 isaccumulated in the memory 82-1 during the times T13 and T03. Light(charges) exposed by the PD (light-receiving device) 81 is accumulatedin the memory 82-2 during the times T03 and T23. Light (charges) exposedby the PD (light-receiving device) 81 is accumulated in the memory 82-1during the times T14 and T04. Light (charges) exposed by the PD(light-receiving device) 81 is accumulated in the memory 82-2 during thetimes T04 and T24.

Control is performed so that it is discharged to the drain during theother times.

In the second gated imaging, as shown in FIG. 16B, imaging is performedby the method of the control C2. That is, light (charges) exposed by thePD (light-receiving device) 81 is accumulated in the memory 82-1 duringthe times T11 and T01. Light (charges) exposed by the PD(light-receiving device) 81 is accumulated in the memory 82-2 during thetimes T01 and T21.

Light (charges) exposed by the PD (light-receiving device) 81 isaccumulated in the memory 82-1 during the times T12 and T02. Light(charges) exposed by the PD (light-receiving device) 81 is accumulatedin the memory 82-2 during the times T02 and T22.

Light (charges) exposed by the PD (light-receiving device) 81 isaccumulated in the memory 82-2 during the times T13 and T03. Light(charges) exposed by the PD (light-receiving device) 81 is accumulatedin the memory 82-1 during the times T03 and T23. Light (charges) exposedby the PD (light-receiving device) 81 is accumulated in the memory 82-2during the times T14 and T04. Light (charges) exposed by the PD(light-receiving device) 81 is accumulated in the memory 82-1 during thetimes T04 and T24.

In the third gated imaging, as shown in FIG. 16C, imaging is performedby the method of the control C3. That is, light (charges) exposed by thePD (light-receiving device) 81 is accumulated in the memory 82-1 duringthe times T11 and T01. Light (charges) exposed by the PD(light-receiving device) 81 is accumulated in the memory 82-2 during thetimes T01 and T21.

Light (charges) exposed by the PD (light-receiving device) 81 isaccumulated in the memory 82-2 during the times T12 and T02. Light(charges) exposed by the PD (light-receiving device) 81 is accumulatedin the memory 82-1 during the times T02 and T22.

Light (charges) exposed by the PD (light-receiving device) 81 isaccumulated in the memory 82-1 during the times T13 and T03. Light(charges) exposed by the PD (light-receiving device) 81 is accumulatedin the memory 82-2 during the times T03 and T23. Light (charges) exposedby the PD (light-receiving device) 81 is accumulated in the memory 82-2during the times T14 and T04. Light (charges) exposed by the PD(light-receiving device) 81 is accumulated in the memory 82-1 during thetimes T04 and T24.

In the j-th (j=1 to 3) gated imaging, after the time T24, chargesaccumulated in the memory 82-1 of each pixel 2 of the image sensor 62are read, and a resulting image I1 j of the gated imaging is obtainedfrom the value of the read pixel. Then, charges accumulated in thememory 82-2 of each pixel 2 of the image sensor 63 are read, and aresulting image I2 j of the gated imaging is obtained from the value ofthe read pixel.

In the resulting image I1 j and the resulting image I2 j, projectedimages of the subjects 53-1 to 53-4 is picked up. Note that in order tomake it easy to see, an image obtained by adding the resulting image I1j and the resulting image I2 j may be created to obtain a sharp image ofthe subjects 53-1 to 53-4.

Now, when the control 1 to the control C3 are compared with each other,whether it is accumulated in the memory 82-1 or the memory 82-2 duringthe time between the times T1 i and T0 i and during the times T0 i to T2i (i=1 to 4) is different. Assumption is made that the case where it isaccumulated in the memory 82-1 during the times T1 i and T0 i and it isaccumulated in the memory 82-2 during the time between the times T0 iand T2 i is a pattern 0. Then, assumption is made that the case where itis accumulated in the memory 82-2 during the times T1 i and T0 i and itis accumulated in the memory 82-1 during the time between the times T0 iand T2 i is a pattern 0. By defining the pattern 0 and the pattern 1 asdescribed above, the control shown in FIGS. 16A, 16B, and 16C is asshown in FIG. 17.

As is clear from the combination of the pattern 0/1 shown in FIG. 17, itcan be considered that a code of three bits is assigned to each of thesubjects 53-1 to 53-4. That is, in the imaging for the subject 53-1,{the case of the control C1, the case of the control C2, and the case ofthe control C3}={0,0,0}.

In the imaging for the subject 53-2, {the case of the control C1, thecase of the control C2, and the case of the control C3}={0,0,1}. In theimaging for the subject 53-3, {the case of the control C1, the case ofthe control C2, and the case of the control C3}={0,1,0}. In the imagingfor the subject 53-4, {the case of the control C1, the case of thecontrol C2, and the case of the control C3}={0,1,1}.

These patterns of three bits are different for the four subjects. Bydifferently setting as described above, it is possible to determinewhich subject has moved.

Further, a total of eight patterns of three bits including threebits={1,1,1} obtained by bit-inverting {the case of the control C1, thecase of the control C2, and the case of the control C3} for the subject53-1, three bits={1,1,0} obtained by bit-inverting {the case of thecontrol C1, the case of the control C2, and the case of the control C3}for the subject 53-2, three bits={1,0,1} obtained by bit-inverting {thecase of the control C1, the case of the control C2, and the case of thecontrol C3} for the subject 53-3, and three bits={1,0,0} obtained bybit-inverting {the case of the control C1, the case of the control C2,and the case of the control C3} for the subject 53-4 differ.Accordingly, it is possible to determine also whether the subject hasmoved forward or backward. Such assignment of the patterns is animportant point of the third embodiment of the present technology.

This will be described in more detail with reference to FIG. 18.

Assumption is made that only the gated imaging by the control C1 isperformed. In such gated imaging, an image 281 is read from the memory82-1, and an image 282 is read from the memory 82-2. In the respectiveimages, four projected images of the subjects 53-1 to 53-4 are imaged.Note that the correspondence relationship between the four projectedimages of the images 281 and 282 and the subjects 53-1 to 53-4 isunknown.

Next, assumption is made that the gated imaging by the control C1 isperformed again. Assumption is made that at this time, any one of thesubjects 53-1 to 53-4 has moved backward. As described above in thesecond embodiment of the present technology, the projected image of thesubject that has moved backward is not projected in an image 283 readfrom the memory 82-1. Meanwhile, it is projected in an image 284 readfrom the memory 82-2.

Therefore, it can be seen that any of the four subjects 53-1 to 53-4 hasmoved backward. However, which subject has moved backward cannot beidentified. Although it only needs to delay the exposure timing byfollowing the moved subject, which of T01 to T04 needs to be delayed isunknown.

Specifically, for example, it may be possibly considered that T03 onlyneeds to be delayed because a subject at a distance D03 has movedbackward and the image 283 and the image 284 are obtained, but this iswrong. This is because the moved subject may be a subject not at thedistance D03 but at a distance D04.

Description will be made again. Since the lower right projected imagedisappears (is not picked up) in the image 283, it can be seen that thesubject corresponding to the lower right projected image has moved.However, at which distance (which of the distances D01 to D04) thissubject has been originally is unknown. Therefore, which of T01 to T04needs to be delayed is unknown.

Meanwhile, by performing the gated imaging three times (imaging by thecontrol C1 to the control C3), it is possible to identify which of T01to T04 is. For example, assumption is made that in the example shown inFIG. 15, the subject at the distance D02 (T02 in terms of time) (thatis, the subject 53-2) has moved forward as shown in FIG. 19. Since thereis not subject 53-2 in the time of a shaded area 271 shown in FIG. 19,the reflected light is not returned. Therefore, in an image read fromthe memory 82-1 by the gated imaging by the control C1, the subject isnot imaged. Then, in an image read from the memory 82-1 by the gatedimaging by the control C2, the subject is not imaged. Then, in an imageread from the memory 82-2 by the gated imaging by the control C3, thesubject is not imaged. In other images, the subject is imaged.

Conversely, in the case where it is not imaged in the image read fromthe memory 82-1 by the gated imaging by the control C1, the image readfrom the memory 82-1 by the gated imaging by the control C2, and theimage read from the memory 82-2 by the gated imaging by the control C3,and imaged in other images, it represents that the subject that has beenat the distance D02 has moved backward, and it is possible to sharplyimage a total of four subjects including other three subjects bydelaying T02 by a small time period in the next gated imaging.

Including also other cases, by resetting T0 i (i=1 to 4) as shown inFIG. 20 and FIG. 21, it is possible to sharply image the four subjectsalso in the next gated imaging.

The example shown in FIG. 20 will be described in the order from thetop. In the case where there is a subject that is not imaged in an imageI11 read from the memory 82-1 in the gated imaging by the control C1, isimaged in an image I12 read from the memory 82-2 in the gated imaging bythe control C1, is not imaged in an image I21 read from the memory 82-1in the gated imaging by the control C2, is imaged in an image I22 readfrom the memory 82-1 in the gated imaging by the control C2, is notimaged in an image I13 read from the memory 82-1 in the gated imaging bythe control C3, and is imaged in an image I23 read from the memory 82-1in the gated imaging by the control C3, the setting unit 92 delays theT01 by a small time period in the next imaging.

In the case where there is a subject that is imaged in the image I11read from the memory 82-1 in the gated imaging by the control C1, is notimaged in the image I12 read from the memory 82-2 in the gated imagingby the control C1, is imaged in the image I21 read from the memory 82-1in the gated imaging by the control C2, is not imaged in the image I22read from the memory 82-1 in the gated imaging by the control C2, isimaged in the image I13 read from the memory 82-1 in the gated imagingby the control C3, and is not imaged in the image I23 read from thememory 82-1 in the gated imaging by the control C3, the setting unit 92advances the T01 by a small time period in the next imaging.

In the case where there is a subject that is not imaged in the image I11read from the memory 82-1 in the gated imaging by the control C1, isimaged in the image I12 read from the memory 82-2 in the gated imagingby the control C1, is not imaged in the image I21 read from the memory82-1 in the gated imaging by the control C2, is imaged in the image I22read from the memory 82-1 in the gated imaging by the control C2, isimaged in the image I13 read from the memory 82-1 in the gated imagingby the control C3, and is not imaged in the image I23 read from thememory 82-1 in the gated imaging by the control C3, the setting unit 92delays the T02 by a small time period in the next imaging.

In the case where there is a subject that is imaged in the image I11read from the memory 82-1 in the gated imaging by the control C1, is notimaged in the image I12 read from the memory 82-2 in the gated imagingby the control C1, is imaged in the image I21 read from the memory 82-1in the gated imaging by the control C2, is not imaged in the image I22read from the memory 82-1 in the gated imaging by the control C2, is notimaged in the image I13 read from the memory 82-1 in the gated imagingby the control C3, and is imaged in the image I23 read from the memory82-1 in the gated imaging by the control C3, the setting unit 92advances the T02 by a small time period in the next imaging.

Further, the example shown in FIG. 21 will be described in the orderfrom the top. In the case where there is a subject that is not imaged inthe image I11 read from the memory 82-1 in the gated imaging by thecontrol C1, is imaged in the image I12 read from the memory 82-2 in thegated imaging by the control C1, is imaged in the image I21 read fromthe memory 82-1 in the gated imaging by the control C2, is not imaged inthe image I22 read from the memory 82-1 in the gated imaging by thecontrol C2, is not imaged in the image I13 read from the memory 82-1 inthe gated imaging by the control C3, and is imaged in the image I23 readfrom the memory 82-1 in the gated imaging by the control C3, the settingunit 92 delays the T03 by a small time period in the next imaging.

In the case where there is a subject that is imaged in the image I11read from the memory 82-1 in the gated imaging by the control C1, is notimaged in the image I12 read from the memory 82-2 in the gated imagingby the control C1, is not imaged in the image I21 read from the memory82-1 in the gated imaging by the control C2, is imaged in the image I22read from the memory 82-1 in the gated imaging by the control C2, isimaged in the image I13 read from the memory 82-1 in the gated imagingby the control C3, and is not imaged in the image I23 read from thememory 82-1 in the gated imaging by the control C3, the setting unit 92advances the T03 by a small time period in the next imaging.

In the case where there is a subject that is not imaged in the image I11read from the memory 82-1 in the gated imaging by the control C1, isimaged in the image I12 read from the memory 82-2 in the gated imagingby the control C1, is imaged in the image I21 read from the memory 82-1in the gated imaging by the control C2, is not imaged in the image I22read from the memory 82-1 in the gated imaging by the control C2, isimaged in the image I13 read from the memory 82-1 in the gated imagingby the control C3, and is not imaged in the image I23 read from thememory 82-1 in the gated imaging by the control C3, the setting unit 92delays the T04 by a small time period in the next imaging.

In the case where there is a subject that is imaged in the image I11read from the memory 82-1 in the gated imaging by the control C1, is notimaged in the image I12 read from the memory 82-2 in the gated imagingby the control C1, is not imaged in the image I21 read from the memory82-1 in the gated imaging by the control C2, is imaged in the image I22read from the memory 82-1 in the gated imaging by the control C2, is notimaged in the image I13 read from the memory 82-1 in the gated imagingby the control C3, and is imaged in the image I23 read from the memory82-1 in the gated imaging by the control C3, the setting unit 92advances the T04 by a small time period in the next imaging.

As described above, according to the third embodiment of the presenttechnology, even in the case where a plurality of subjects move in thedepth direction, it is possible to achieve the gated imaging that iscapable of continuing to sharply image the subjects by appropriatelyfollowing the subjects. Note that it is different from the secondembodiment of the present technology in that it supports a plurality ofsubjects.

<Operation of Gated Imaging System>

Next, the gated imaging processing by the gated imaging system 250 shownin FIG. 15 and FIG. 19 will be described with reference to the flowchartof FIG. 22.

In Step S201, the setting unit 92 specifies four distances at whichimaging is to be performed. In this example, the four distances are D01,D02, D03, and D04.

The setting unit 92 sets T01=2*D01/c, T02=2*D02/c, T03=2*D03/c, andT04=2*D04/c, (c representing a speed of light) in Step S202, andT11=T01−W, T21=T01+W, T12=T02−W, T22=T02+W, T13=T03−W, T23=T03+W,T14=T04−W, and T24=T04+W (where W represents the width of pulsed light)in Step S205.

In Step S204, the exposure control unit 91 performs gated imaging by thecontrol C1, reads charges in the memory 82-1 to obtain a resulting imageI11, and reads charges in the memory 82-2 to obtain a resulting imageI21. Then, the exposure control unit 91 outputs, as a resulting image Iof the present gated image, an image obtained by adding the resultingimage I11 and the resulting image I21 from the output terminal 72.

In Step S205, the exposure control unit 91 performs gated imaging by thecontrol C2, reads charges in the memory 82-1 to obtain a resulting imageI12, and reads charges in the memory 82-2 to obtain a resulting imageI22. Then, the exposure control unit 91 outputs, as a resulting image Iof the present gated image, an image obtained by adding the resultingimage I12 and the resulting image I22 from the output terminal 72.

In Step S206, the exposure control unit 91 performs gated imaging by thecontrol C3, reads charges in the memory 82-1 to obtain a resulting imageI13, and reads charges in the memory 82-2 to obtain a resulting imageI23. Then, the exposure control unit 91 outputs, as a resulting image Iof the present gated image, an image obtained by adding the resultingimage I13 and the resulting image I23 from the output terminal 72.

In Step S207, the setting unit 92 changes T0 i (i=1 to 4) in the casewhere it applies to any of the tables shown in FIG. 20 and FIG. 21.

After that, the processing returns to Step S203, and the subsequentprocessing is repeated.

Note that the case where the number of subjects is four has beendescribed above. In this case, it needs three bits to distinguishbetween the four subjects and between the forward movement and thebackward movement. In order to achieve this, three times of gatedimaging by the control C1 to the control C3 has been performed.Generalizing the number of subjects (number of distances at whichsubjects to be imaged are) is as follows. That is, in order to performthe gated imaging on (2 to the s-th power) subjects, s+1 times of gatedimaging is performed. In each of the s+1 times of gated imaging, inwhich of the memory 82-1 and the memory 82-2 the first half and thelatter half of reflection of pulsed light is accumulated only needs tobe different for the pattern of s+1 bits including the bit inversion.

4. Fourth Embodiment

In the above-mentioned first to third embodiments of the presenttechnology, assumption is made that when performing the first gatedimaging, the distance of the subject is already known. However, inactual operation, the distance of the subject is unknown at first inmost cases.

In this regard, in a fourth embodiment, a method of determining adistance of a subject in a short time in the case where the distance ofthe subject is unknown will be described. That is, it is possible toembody the best of the present technology by identifying the distance ofthe subject with the fourth embodiment of the present technology andthen executing the first to third embodiments of the present technology.

Next, the gated imaging processing in the case of the fourth embodimentwill be described with reference to the flowchart of FIG. 23. Note thatdescription will be made using the gated imaging apparatus 250 describedabove with reference to FIG. 15 and FIG. 19.

In Step S301, the setting unit 92 sets a maximum imaging range Dmin toDmax. Note that Dmin<Dmax.

In Step S302, the setting unit 92 sets Tmin=2*Dmin/c and Tmax=2*Dmax/c.

In Step S303, the setting unit 92 performs the processing of sub-routineA, and then, finishes the gated imaging processing. Subsequently, theprocessing of sub-routine A in Step S303 will be described withreference to FIG. 24 to FIG. 26.

In Step S321 shown in FIG. 24, the setting unit 92 setsTmid=(Tmin+Tmax)/2. In Step S322, the exposure control unit 91 performsgated imaging. That is, the exposure control unit 91 emits pulsed lightfrom the light emitting unit 61, and accumulates light (charges)received (exposed) by the PD (light-receiving device) 81 in the memory82-1 during times Tmin to Tmid. During times Tmid to Tmax, the exposurecontrol unit 91 accumulates light (charges) received (exposed) by the PD(light-receiving device) 81 in the memory 82-2. During the other times,light (charges) received (exposed) by the PD (light-receiving device) 81is discharged to the drain.

In Step S323, the exposure control unit 91 reads charges accumulated inthe memory 82-1 of each pixel 2 of the image sensor 62 after the timeTmax, and obtains the resulting image I1 of the gated imaging from thevalue of the read pixel. Further, the exposure control unit 91 readscharges accumulated in the memory 82-2 of each pixel 2 of the imagesensor 62, and obtains the resulting image I2 of the gated imaging fromthe value of the read pixel.

In Step S324, the subject determination unit 261 determines whether ornot a significant subject is imaged in the resulting image I1. In thecase where it is determined in Step S324 that a significant subject isimaged in the resulting image I1, the processing proceeds to Step S325.

In Step S325, the setting unit 92 determines whether or notTmid−Tmin<2*Δ/c. Note that Δ represents the accuracy of the distance tobe specified. In the case where it is determined in Step S325 thatTmid−Tmin is not less than 2*Δ/c, the processing proceeds to Step S326.The setting unit 92 sets Tmin=Tmin and Tmax=Tmid in Step S326, andperforms the processing of sub-routine A (processing being described atthe present) again in Step S327.

Further, in the case where it is determined in Step S325 thatTmid−Tmin<2*Δ/c, the processing proceeds to Step S328. The setting unit92 sets Ttmp=(Tmin+Tmid)/2 in Step S328, and outputs a value of Tmid*c/2as the distance at which the subject 53 is in Step S329.

After Step S327 or Step S329, the processing proceeds to S330 shown inFIG. 26. Meanwhile, in the case where it is determined in Step S324 thata significant subject is not imaged in the resulting image I1, theprocessing proceeds to Step S330 shown in FIG. 26.

In Step S330 shown in FIG. 26, the subject determination unit 261determines whether or not a significant subject is imaged in theresulting image I2. In the case where it is determined in Step S330 thata significant subject is imaged in the resulting image I2, theprocessing proceeds to Step S331.

In Step S331, the setting unit 92 determines whether or notTmax−Tmin<2*Δ/c. Note that Δ represents the accuracy of the distance tobe specified. In the case where it is determined in Step S331 thatTmax−Tmin is not less than 2*Δ/c, the processing proceeds to Step S332.The setting unit 92 sets Tmin=Tmid and Tmax=Tmax in Step S332, andperforms the processing of sub-routine A (processing being described atthe present) again in Step S333.

Further, in the case where it is determined in Step S331 thatTmax−Tmin<2*Δ/c, the processing proceeds to Step S334. The setting unit92 sets Ttmp=(Tmin+Tmax)/2 in Step S334, and outputs a value of Tmid*c/2as the distance at which the subject 53 is in Step S335.

After Step S333 or Step S335, the processing returns to S303 shown inFIG. 23, and the gated imaging processing is finished. Meanwhile, in thecase where it is determined in Step S330 that a significant subject isnot imaged in the resulting image 2, the processing returns to S303shown in FIG. 23 and the gated imaging processing is finished.

Note that description has been made in the above on the assumption thatone pixel has the configuration shown in FIG. 6. That is, light exposed(received) by the PD (light-receiving device) 81 is converted intocharges, and the charges are accumulated in the memory (chargeaccumulation unit) 82. Meanwhile, in the case where there are m (mrepresenting an integer not less than 3) memories, the configuration isas follows.

That is, light exposed by the PD 81 is converted into charges, and thecharges are accumulated in any of the memories 82-k (k=1 to m). In thiscase, it only needs to narrow the search range by dividing the imagingrange not into two ranges unlike the above example but into m ranges.

As described above, according to the present technology, it is possibleto receive light a plurality of times temporally per pulse emission.Accordingly, it is possible to sharply image a plurality of subjects,know the direction of movement of a subject in the depth direction, andcontinue to image a moving subject by following the moving subject.

Note that although the configuration in which the present technology isapplied to the CMOS solid-state imaging apparatus has been described inthe above, the present technology may be applied to a solid-stateimaging apparatus such as a CCD (Charge Coupled Device) solid-stateimaging apparatus.

5. Fifth Embodiment (Usage Example of Image Sensor)

FIG. 27 is a diagram showing a usage example of the above-mentionedsolid-state imaging apparatus.

The above-mentioned solid-state imaging apparatus (image sensor) can beused in various cases for sensing light such as visible light, infraredlight, ultraviolet light, and X-rays as follows, for example.

An apparatus for photographing images to be viewed, such as a digitalcamera and a camera-equipped mobile apparatus

An apparatus used in the traffic field, such as a car-mounted sensorthat photographs front/rear/periphery/inside of an automobile, asurveillance camera that monitors running vehicles and roads, and adistance measurement sensor that measures distances among vehicles, forsafe driving including automatic stop, recognition of a drivercondition, and the like

An apparatus used in the home electronics field such as a televisionreceiver, a refrigerator, and an air conditioner, for photographinggestures of users and executing apparatus operations according to thegestures

An apparatus used in the medical and healthcare filed, such as anendoscope and an apparatus that performs blood vessel photographing byreceiving infrared light

An apparatus used in the security field, such as a surveillance camerafor crime-prevention purposes and a camera for person authenticationpurposes

An apparatus used in the beauty care field, such as a skin measurementapparatus that photographs skins and a microscope that photographsscalps

An apparatus used in the sports field, such as an action camera and awearable camera for sports purposes

An apparatus in the agriculture field, such as a camera for monitoringstates of fields and crops

6. Sixth Embodiment (Example of Electronic Apparatus)

<Configuration Example of Electronic Apparatus>

Further, the present technology is not necessarily applied to asolid-state imaging apparatus, and is applicable also to an imagingapparatus. Note that the imaging apparatus represents a camera systemsuch as a digital still camera and a digital video camera, and anelectronic apparatus having an imaging function such as a mobile phone.Note that a module-like form mounted on an electronic apparatus, i.e., acamera module is an imaging apparatus in some cases.

Now, a configuration example of an electronic apparatus according to thepresent technology will be described with reference to FIG. 28.

An electronic apparatus 500 shown in FIG. 28 includes a solid-stateimaging apparatus (device chip) 501, an optical lens 502, a shutterapparatus 503, a drive circuit 504, and a signal processing circuit 505.As the solid-state imaging apparatus 501, the above-mentionedsolid-state imaging apparatus 1 (image sensor 62) according to thepresent technology is provided. Further, in the electronic apparatus500, the above-mentioned light emitting unit 61 is provided as a lightemitting unit (not shown).

The optical lens 502 forms an image of image light (incident light) froma subject on the imaging surface of the solid-state imaging apparatus501. Accordingly, signal charges are accumulated in the solid-stateimaging apparatus 501 for a certain period of time. The shutterapparatus 503 controls the light irradiation period of time and lightblocking period of time for the solid-state imaging apparatus 501.

The drive circuit 504 supplies drive signals for controlling a signaltransfer operation of the solid-state imaging apparatus 501, a shutteroperation of the shutter apparatus 503, and a light emission operationof the light emitting unit (not shown). As the drive circuit 504, theabove-mentioned exposure control unit 91 according to the presenttechnology is provided. The drive circuit 504 controls each operation byusing parameters set by a CPU (not shown). As the CPU (not shown), theabove-mentioned setting unit 92 according to the present technology isprovided. By the drive signal (timing signal) supplied from the drivecircuit 504, the solid-state imaging apparatus 501 transfers a signal.The signal processing circuit 505 performs various kinds of signalprocessing on the signal output from the solid-state imaging apparatus501. The video signal on which the signal processing has been performedis stored in a storage medium such as a memory or output to a monitor.

Note that Steps describing the series of processing described herein ofcourse include processing performed in time series in the describedorder and the series of processing do not necessarily need to beprocessed in time series. The series of processing may also includeprocessing performed in parallel or individually.

Further, embodiments of the present disclosure are not limited to theabove-mentioned embodiments and may be variously changed withoutdeparting from the essence of the present disclosure.

Furthermore, in the above, the structure described as one apparatus (orprocessing unit) may be divided into a plurality of apparatuses (orprocessing units). In contrast, the structures described as theplurality of apparatuses (or processing units) may be configured as oneapparatus (or processing unit). Further, to the structures of theapparatuses (or processing units), additional structure other than thestructures described above may be of course provided. Further, a part ofthe structure of a certain apparatus (or processing unit) may beincluded in the structure of another apparatus (or another processingunit), if the structure and operation of the entire system issubstantially equal thereto. That is, the present technology is notlimited to the above embodiments and can be variously modified withoutdeparting from the essence of the present technology.

The favorable embodiments of the present disclosure are described abovein detail with reference to the attached drawings. However, the presentdisclosure is not limited to the above examples. It is obvious thatthose skilled in the art to which the present disclosure belongs canconceive various modified examples within the scope of the technicalidea described in the scope of the appended claims, and it is understoodthat those examples of course belong to the technical scope of thepresent disclosure.

REFERENCE SIGNS LIST

1 solid-state imaging apparatus

2 pixel

21 gated imaging apparatus

22 fog

23 subject

31 control unit

32 light emitting unit

33 imaging unit

50 gated imaging system

51 gated imaging apparatus

52, 52-1, 52-2 fog

53, 53-1 to 53-3 subject

61 light emitting unit

62 image sensor

70 gated imaging apparatus

71 control unit

72 output terminal

81 PD

82-1, 82-2 memory

83 switch

91 setting unit

92 exposure control unit

100 gated imaging system

101 automobile

111 pulsed light

112 reflected light

150 gated imaging system

200 gated imaging system

211 pillar

212 wall

250 gated imaging system

261 subject determination unit

281 to 284 image

500 electronic apparatus

501 solid-state imaging apparatus

502 optical lens

503 shutter apparatus

504 drive circuit

505 signal processing circuit

The invention claimed is:
 1. An imaging apparatus, comprising: a lightemitting unit that performs pulse emission; a light reception unit thatreceives light; an exposure control unit that causes the light receptionunit to perform a plurality of times of exposure per pulse emission fromthe light emitting unit; and a setting unit that sets, depending on apredetermined imaging distance range, a start time and an end time ofthe plurality of times of exposure by using timing of the pulse emissionas a reference to perform imaging processing on a subject within thepredetermined imaging distance range.
 2. The imaging apparatus accordingto claim 1, wherein the predetermined imaging distance range includesone to n (n being an integer not less than 2) imaging distance ranges,and when the i-th (i=1 to n) distance range of the predetermined imagingdistance range is represented by Min(i) to Max(i) (Min(i)<Max(i)), thenumber of times of the exposure is n, and the setting unit sets a starttime and an end time of the j-th (j=1 to n) exposure of the n times ofexposure to (2×Min(i))/c and (2×Max(i))/c (c representing a speed oflight), respectively.
 3. The imaging apparatus according to claim 1,wherein an amount of light received by the light reception unit isstored in any of 1 to m (m representing an integer not less than 2)memories, and when the predetermined imaging distance range isrepresented by Min to Max (Min<Max), the number of times of the exposureis m, the setting unit sets a start time and an end time of the j-th(j=1 to n) exposure of the m times of exposure to(2×Min)/c+2×(Max−Min)×(j−1)/c/m and 2×Min/c+2×(Max−Min)×j/c/m (crepresenting a speed of light), respectively, and the control unitperforms such control that an amount of light received in the j-th (j=1to n) exposure of the m times of exposure is stored in the j-th memoryof the m memories.
 4. The imaging apparatus according to claim 3,further comprising a subject identification unit that identifies amemory storing no data of a projected image of the subject out of the mmemories, wherein in a case where the memory storing no data of theprojected image of the subject identified by the subject identificationunit is the p-th memory and p=m or p substantially equals to m, asmaller value is reset for at least one of a value of the Min and avalue of the Max, and a parameter for next imaging is determined, or ina case where the memory storing no data of the projected image of thesubject identified by the subject identification unit is the p-th memoryand p=1 or p substantially equals to 1, a larger value is reset for atleast one of a value of the Min and a value of the Max, and a parameterfor next imaging is determined.
 5. The imaging apparatus according toclaim 1, wherein in each of s+1 (s representing an integer not lessthan 1) times of imaging processing on the subject, an amount of lightreceived by the light reception unit is stored in any of a first memoryand a second memory, the predetermined imaging distance range includes 1to (2 to the s-th power) imaging distance ranges, and when the k-th (k=1to 2 to the s-th power) distance range of the predetermined imagingdistance range is represented by Min(k) to Max(k) (Min(k)<Max(k)), thenumber of times of the exposure is 2×(2 to the s-th power), the settingunit sets a start time and an end time of the 2×k−1-th (k=1 to 2 to thes-th power) exposure of the (2 to the s-th power) times of exposure to2×Min(k)/c, 2×Max(k)/c+2×(Max(k)−Min(k)/c/2, and 2×Max(k)/c (crepresenting a speed of light), respectively, and sets a start time andan end time of the 2×k-th (k=1 to 2 to the s-th power) exposure of the(2 to the s-th power) times of exposure to2×Min(k)/c+2×(Max(k)−Min(k))/c/ and 2×Max(k)/c (c representing a speedof light), and in the q-th (q representing 1 to s+1) imaging processing,the control unit performs such control that an amount of light receivedby the light reception unit in the 2×k−1-th (k=1 to 2 to the s-th power)exposure of the (2 to the s-th power) times of exposure is stored in ther(k,q)-th (r(k,q) representing 1 or 2) memory of the first memory andthe second memory, and an amount of light received by the lightreception unit in the 2×k-th (k=1 to 2 to the s-th power) exposure ofthe (2 to the s-th power) times of exposure is stored in a memory otherthan the r(k,q)-th (r(k,q) representing 1 or 2) memory of the firstmemory and the second memory, and determines r(k,q) so that a sequence{r(k,1), r(k,2), . . . r(k,s+1)} is different from a sequence {r(k′,1),r(k′,2), . . . r(k′,s+1): where k′≠k} and a sequence {3−r(k′,1),r(k′,2), . . . r(k′,s+1: where k′≠k) for k being an arbitrary value. 6.The imaging apparatus according to claim 5, further comprising a subjectidentification unit that identifies a memory storing no data of aprojected image of the subject out of the first memory and the secondmemory, wherein in each of s+1 (s representing an integer not lessthan 1) times of imaging processing on the subject, the setting unitresets, corresponding to the number of the memory storing no data of theprojected image of the subject identified by the subject identificationunit, a smaller value for at least one of a value of the Min and a valueof the Max, and determines a parameter for next imaging.
 7. The imagingapparatus according to claim 3, further comprising a subjectidentification unit that identifies the j-th (j=1 to n) memory storingdata of a projected image of the subject out of the m memories, whereinwhen the number of the memory storing the data of the projected image ofthe subject identified by the subject identification unit is q, thesetting unit newly sets the Min to 2×Min/c+2×(Max−Min)×(q−1)/c/m and theMax to 2×Min/c+2×(Max−Min)×q/c/m (c representing a speed of light), anddetermines a parameter for next imaging.
 8. An electronic apparatus,comprising: a light emitting unit that performs pulse emission; a lightreception unit that receives light; an exposure control unit that causesthe light reception unit to perform a plurality of times of exposure perpulse emission from the light emitting unit; and a setting unit thatsets, depending on a predetermined imaging distance range, a start timeand an end time of the plurality of times of exposure by using timing ofthe pulse emission as a reference to perform imaging processing on asubject within the predetermined imaging distance range.